Abstract: An NMR apparatus includes a superconducting magnet assembly, a cryostat having a vacuum vessel, a refrigeration stage that can be operated at a temperature of <100 K, and a magnet coil system that comprises a cold bore into which a room temperature access of the cryostat engages. The NMR apparatus also includes an NMR probe with probe components cooled to an operating temperature of <100 K. The probe components are arranged between the cold bore and the room temperature access into the cold bore, radially inside the cold bore but outside the room temperature access. The vacuum vessel includes an opening that can be closed by a lock valve. A lock chamber is directly connected to the opening, such that the cooled probe components can be installed and/or removed through the opening and lock valve without breaking the vacuum in the vacuum vessel of the cryostat.

Abstract: A cryostat system is kept at a cryogenic operating temperature without providing or supplying cryogenic fluids by a cryocooler. The cryostat system includes a superconducting magnet arrangement and a heat sink apparatus to prolong the time before the superconducting magnet arrangement quenches/returns to the normally conducting state if active cooling fails. The heat sink apparatus includes magnetocaloric material and is thermally connected to the superconducting magnet arrangement and/or to parts of the cryostat system through which ambient heat can flow to the superconducting magnet arrangement. In this way, the cryostat system can be operated in a truly “cryogen-free” manner while maintaining a sufficiently long time to quench in the event of potential operational malfunctions.

Abstract: A DNP apparatus includes a cryostat (7) having an opening (8) and a loading path for a sample (1), the loading path extending from the opening to a sample receptacle (29), with a cryomagnet and a microwave source (2) as well as a configuration for supplying microwave radiation from the microwave source to the sample, which comprises a microwave path extending directly to the sample. The microwave path extends spatially separately from the loading path and the configuration for supplying microwave radiation has at least one microwave feed-through passing through one or more walls of the cryostat. The microwave path is incident on the sample from a direction opposite to the loading path or from a sideward direction at right angles to or at an inclination with respect to the axis of the loading path. This leads to simple and efficient polarization of the electron spins in the sample.

Abstract: A method for converting a cryostat configuration (1) having a first container (2) with a liquid helium bath (3) and a second container (6) which is filled with liquid nitrogen (7) is characterized in that a cooling medium (12) which is in a gaseous state at a temperature of 60K and a pressure of 1 bar, is introduced into the second container and is cooled by a refrigerator (16) by means of a cooling circuit (11), the coolant lines of which are guided into the second container, to an operating temperature of ?60K. With this retrofit for existing cryostat configurations that utilize both liquid helium and also liquid nitrogen for cooling a superconducting coil, use of liquid nitrogen can be completely avoided and the evaporation rate of the liquid helium can also be considerably reduced without having to re-liquefy the cryogens used.

Abstract: A DNP apparatus includes a cryostat (7) having an opening (8) and a loading path for a sample (1), the loading path extending from the opening to a sample receptacle (29), with a cryomagnet and a microwave source (2) as well as a configuration for supplying microwave radiation from the microwave source to the sample, which comprises a microwave path extending directly to the sample. The microwave path extends spatially separately from the loading path and the configuration for supplying microwave radiation has at least one microwave feed-through passing through one or more walls of the cryostat. The microwave path is incident on the sample from a direction opposite to the loading path or from a sideward direction at right angles to or at an inclination with respect to the axis of the loading path. This leads to simple and efficient polarization of the electron spins in the sample.

Abstract: A method for converting a cryostat configuration (1) having a first container (2) with a liquid helium bath (3) and a second container (6) which is filled with liquid nitrogen (7) is characterized in that a cooling medium (12) which is in a gaseous state at a temperature of 60K and a pressure of 1 bar, is introduced into the second container and is cooled by a refrigerator (16) by means of a cooling circuit (11), the coolant lines of which are guided into the second container, to an operating temperature of ?60K. With this retrofit for existing cryostat configurations that utilize both liquid helium and also liquid nitrogen for cooling a superconducting coil, use of liquid nitrogen can be completely avoided and the evaporation rate of the liquid helium can also be considerably reduced without having to re-liquefy the cryogens used.

Abstract: A cryostat configuration with a vacuum vessel (1) and a cryogen vessel (2) built into it, and a sleeve (8), into which a cryocooler (7) is built, wherein the upper, warm end of the sleeve is connected to the outer jacket and the lower, cold end facing the cryogen vessel is hermetically sealed by a sleeve base (9) is characterized in that the cryogen vessel is hermetically sealed except for a gas capillary (13) and filled with gaseous fluid (12) at a pressure below the vapor pressure of the liquid phase of the fluid at the corresponding operating temperature and the coldest stage of the cryocooler is connected to the heat exchanger (11) disposed inside the cryogen vessel in a manner that ensures good thermal conduction.